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Ravaioli, Umberto Kan, Edwin Chihchuan 2011-05-07T13:16:44Z 2011-05-07T13:16:44Z 10000-01-01 1992 Numerical modeling of nonstationary transport effects using partial differential equations derived from the Boltzmann Transport Equation (BTE) is investigated. Augmented drift-diffusion (ADD) models and improved energy transport (ET) models for submicron device simulation are constructed and numerically implemented. Analytical derivation of the length coefficient for the ADD models is presented for both single- and multi-valley approximations. Results of typical $n\sp+ - n - n\sp+$ ballistic diodes for Si and GaAs are presented. The extension of the ADD model to two dimensions is then formulated, and the implementation problems with the standard box integration method, as used in conventional drift-diffusion (DD) models, are examined. Improved ET models are derived from the zeroth and second moments of the Boltzmann transport equation and from the presumed function form of the even part of the distribution function. Energy band nonparabolicity and non-Maxwellian distribution effects are included to first order. The ET models are amenable to an efficient self-consistent discretization, with standard techniques, taking advantage of the similarity between current and energy flow equations. Numerical results for ballistic diodes and MOSFETs are presented. Typical spurious velocity overshoot spikes, obtained in conventional hydrodynamics simulations of ballistic diodes, are virtually eliminated. By comparing the formulation of the ET and HD models, we find that the spurious spike is caused by the momentum relaxation time approximation and the resulting form of the thermal diffusion terms. Calculations based on a two-carrier-population model, at the anode junction, further confirm our analysis of the spurious spike. Made available in DSpace on 2011-05-07T13:16:44Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9215834.pdf: 3187102 bytes, checksum: 23f90715df01556a050d0e5098e6f6f0 (MD5) Previous issue date: 1992 Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T14:52:40Z Item is restricted indefinitely. Restriction data tranferred 2014-07-01T11:24:16-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission ETDs are only available to UIUC Users without author permission U of I Only AAI9215834 (UMI)AAI9215834 http://hdl.handle.net/2142/21707 eng Copyright 1992 Kan, Edwin Chihchuan Mathematics Engineering, Electronics and Electrical Physics, Condensed Matter Numerical models for the simulation of nonstationary effects in submicron semiconductor devices text Electrical and Computer Engineering Electrical Engineering University of Illinois at Urbana-Champaign Dissertation Ph.D.